#ifndef _MEMDC2_H_
#define _MEMDC2_H_

//////////////////////////////////////////////////
// CMemDC - memory DC
//
// Author: Keith Rule
// Email:  keithr@europa.com
// Copyright 1996-2002, Keith Rule
//
// You may freely use or modify this code provided this
// Copyright is included in all derived versions.
//
// History - 10/3/97 Fixed scrolling bug.
//               Added print support. - KR
//
//       11/3/99 Fixed most common complaint. Added
//            background color fill. - KR
//
//       11/3/99 Added support for mapping modes other than
//            MM_TEXT as suggested by Lee Sang Hun. - KR
//
//       02/11/02 Added support for CScrollView as supplied
//             by Gary Kirkham. - KR
//
// This class implements a memory Device Context which allows
// flicker free drawing.

class CMemDC2 : public CDC {
private:       
	CBitmap    m_bitmap;        // Offscreen bitmap
	CBitmap*   m_oldBitmap;     // bitmap originally found in CMemDC
	CDC*       m_pDC;           // Saves CDC passed in constructor
	CRect      m_rect;          // Rectangle of drawing area.
	BOOL       m_bMemDC;        // TRUE if CDC really is a Memory DC.
public:

	CMemDC2(CDC* pDC, const CRect* pRect = NULL) : CDC()
	{
		ASSERT(pDC != NULL); 

		// Some initialization
		m_pDC = pDC;
		m_oldBitmap = NULL;
		m_bMemDC = !pDC->IsPrinting();

		// Get the rectangle to draw
		if (pRect == NULL) {
			pDC->GetClipBox(&m_rect);
		} else {
			m_rect = *pRect;
		}

		if (m_bMemDC) {
			// Create a Memory DC
			CreateCompatibleDC(pDC);
			pDC->LPtoDP(&m_rect);

			m_bitmap.CreateCompatibleBitmap(pDC, m_rect.Width(), 
				m_rect.Height());
			m_oldBitmap = SelectObject(&m_bitmap);

			SetMapMode(pDC->GetMapMode());

			SetWindowExt(pDC->GetWindowExt());
			SetViewportExt(pDC->GetViewportExt());

			pDC->DPtoLP(&m_rect);
			SetWindowOrg(m_rect.left, m_rect.top);
		} else {
			// Make a copy of the relevent parts of the current 
			// DC for printing
			m_bPrinting = pDC->m_bPrinting;
			m_hDC       = pDC->m_hDC;
			m_hAttribDC = pDC->m_hAttribDC;
		}

		// Fill background 
		FillSolidRect(m_rect, pDC->GetBkColor());
	}

	~CMemDC2()      
	{          
		if (m_bMemDC) {
			// Copy the offscreen bitmap onto the screen.
			m_pDC->BitBlt(m_rect.left, m_rect.top, 
				m_rect.Width(),  m_rect.Height(),
				this, m_rect.left, m_rect.top, SRCCOPY);            

			//Swap back the original bitmap.
			SelectObject(m_oldBitmap);        
		} else {
			// All we need to do is replace the DC with an illegal
			// value, this keeps us from accidentally deleting the 
			// handles associated with the CDC that was passed to 
			// the constructor.              
			m_hDC = m_hAttribDC = NULL;
		}       
	}

	// Allow usage as a pointer    
	CMemDC2* operator->() 
	{
		return this;
	}       

	// Allow usage as a pointer    
	operator CMemDC2*() 
	{
		return this;
	}
};

#endif	//_MEMDC2_H_
